The present invention refers to a lock, to be used particularly on boat hatches and alike, which can be operated both from outside and from inside, in order to open or close the movable shutter of a hatch, relatively to its fixed frame. In particular, in this lock it is optional to make operative or inoperative, according to circumstances, the outside operation while retaining at all times the inside one.
Locks of this type are already known, but they require a complex manipulation in order to make inoperative the outside operation. A further disadvantage of the existing locks is due to the fact that the outside operation is performed either by means of a special handle which is an integral part of the lock itself, thus increasing its cost, or by means of a special key, with all the related inconveniences, such as, for instance, the loss of the key.